Container for hot-filling liquids

ABSTRACT

The invention relates to a packaging means, hereinbelow also: container, which is suitable for the hot-filling of food products in liquid form. The container comprises an upper base of a metal or of a metal alloy having an opening for receiving the liquid and a lower base of a metal or an alloy having an air admission. The upper base and the lower base are sealingly connected with a wall body of a metal or an alloy at a respective upper or lower end of the wall body and form a hollow space for receiving the liquid. Between the lower base and the lower end of the wall body sealingly engaging the lower base, a film is provided which can cause a volume reduction of the hollow space.

PRIORITY CLAIM

Applicants claim the priority of German Patent Application No. DE 102015 111 113.6, filed on Jul. 9, 2015.

FIELD OF THE INVENTION

The invention relates to a packaging means, hereafter also container,which is suitable for hot-filling of food products in liquid form.

TECHNICAL BACKGROUND

The filling or bottling of liquids, in particular in the field of foodproducts, poses high requirements to the packaging and the packagingprocess, because producers of food products strive to protect theirproduct from the premature spoilage. Liquids are commonly introducedinto a container, in particular bottles, in a so called fill and sealprocess by means of a fill and seal machine in a predetermined amountand are then sealed. The embodiment of the fill and seal machine isdependent on the liquid to be filled.

In order to allow for microbiological hygiene during the filling of theliquids so called aseptic filling machines can be employed. Asepticfilling machines are filling machines which fill sterile chargeprotected against a re-contamination into a packaging material which isusually pre-germinated or produced free of germs within the packagingmachine (cf.: VDMA 8742, “Aspetische Verpackungsmaschinen für dieNahrungsmittelindustrie: Mindestanforderungen und Rahmenbedingungen füreinen bestimmungsgemäβen Betrieb” (“Aseptic packaging machines for thefood product industrie: Minimum requirements and border conditions for acompliant operation”), available at http://www.vdma.org).

Alternatively, filling systems for the hot-filling of food product canbe used, in which the food product (liquid) is filled into the packagingmeans at temperatures of usually more than 80° C., wherein themicrobiological hygiene can be ensured due to the high filling intemperature of the food product. The invention proposes a containerwhich is in particular suitable for the hot-filling of food products, inparticular of liquids.

In order to avoid the spoilage of the hot-filled food products as longas possible, it is also required to seal the packaging means afterfilling under hygienic border conditions such that no germs or moldfungi can get into the inside of the packaging. Therefore, gas-tightclosures are mostly selected, which prevent not only the penetration ofgerms or fungi but also of gases, in particular oxygen, into thepackaging inside and/or the exiting of gases (such as CO₂) from thepackaging interior. When using containers which at least predominantlyconsist of metal (or a metal alloy), after closing the container, thevolume reduction of the hot filled food product due to the cooling ofthe liquid leads to hydrostatic forces within the container which causetensile forces in the upper base, the lower base and the wall body ofthe container which, dependent on the shape of the container lead todeformation of the container.

In particular for containers having a cylindrical base shape, due todeviations in the material of the wall body (for example in thethickness) the tensile forces cause usually local dents which arenevertheless very noticeable to the observer and greatly impair theaesthetic appearance of the container shape. Since the aestheticappearance nowadays plays a very important role for the product purchasethrough the end-customer, it is desirable to avoid such deformationswhich impair the aesthetic appearance of the container.

SUMMARY OF THE INVENTION

It is therefore an objective of the invention to propose a containerhaving a wall body (and optionally also a lower base and/or upper base)of metal (or a metal alloy) which does not go out of shape due to actingtensile forces after hot-filling and gas-tight sealing of the container,so that the aesthetic appearance of the container shape remains intact.Furthermore it is another objective of the invention to provide aparticularly simple and/or inexpensive design of such a container.

It is another partial objective of the invention to design the containerand in particular the closure such that changes in taste through contactof the metal constituents with the filled liquid are inhibited.

An aspect underlying the invention is the use of a film or foil, whichis attached for example between the lower base and the lower end of thewall body of the container, sealingly engaging the lower base of thecontainer. The film is selected with regard to its material propertiessuch that it can cause a volume reduction of the container interior whenthe external pressure of the container (for example the atmosphericpressure) is larger than the pressure within the container interior.

In an embodiment of the invention, the film can decrease the volume inthe container interior such that after hot-filling a liquid into thecontainer and after the air-tight (or gas-tight) sealing or closingthereof, the compression forces occurring due to the subsequent coolingof liquid are absorbed. The absorption of the compression forces leadsto deformation only of the film causing the volume reduction of thecontainer interior. Thereby it can be ensured that the wall body formingthe side wall of the container is not deformed through the tensileforces acting thereon in a manner which impairs the aesthetic appearancethereof.

According to one embodiment of the invention, a container for receivinga liquid is provided. The container comprises an upper base made of ametal or of a metal alloy. The upper base can also be called first base,top end or upperside. The upper base has an opening for receiving theliquid. The filling, in particular the hot-filling, of the liquid intothe container may be performed by (hot-) filling the liquid through theopening of the upper base into the container. The container furthercomprises a lower base, which can also be called second base, bottomend, or underside. The lower base may be made of a metal or a metalalloy. The lower base has an air admission or air passage, which forexample can be realized by one or more holes which are large enough tolet air pass through. The upper base and the lower base are connectedwith a wall body made of a metal or of a metal alloy at a respectiveupper or lower end of the wall body so that a hollow space for receivingthe liquid is formed. This hollow space for receiving the liquid ishereafter also referred to as a container interior. The wall body canalso be referred to as side wall of the container or container sidewall.Between the lower base and the lower end of the wall body sealinglyengaging with the lower base, furthermore, a film is provided which cancause a volume reduction of the hollow space. The intermediate spacebetween the film deformed for volume reduction and the lower base of thecontainer shall not contain the liquid to be received by the containerand is therefore not part of the hollow space.

In an exemplary embodiment of the invention, the wall body (andoptionally the upper base and/or the lower base) are deformation-rigidin relation to the film. In particular, the material of the wall body,the upper base and/or the lower base can to this end have a modulus ofelasticity which is at least 5 times, preferably at least 10 times,further preferred at least 100 times, as large as of the modulus ofelasticity of the film material.

In an exemplary embodiment of the invention, the film absorbs thecompression forces caused by cooling of the hot-filled liquid afterair-tight sealing of the opening. It it can thus be possible that thefilm completely absorbs the compression forces caused during the coolingof the liquid (insofar as possible). Ideally, the material of the film,in comparison to the material of the wall body (and optionally of theupper base and/or of the lower base), is selected such that the filmcompensates the compression forces such that the outer shape of the wallbody of the container does not visibly (for a human observer) deformduring cooling of the hot-filled liquid due to tensile forces.

The wall body of the container is in one embodiment formed as a hollowcylinder. The cylinder edges are sealingly connected with the lower baseand to the upper base. The material properties of the film are laid outsuch that the film advantageously absorbs the compression forces so(completely) that the cylindrical shape of the wall body is maintainedafter cooling of the liquid.

In a further embodiment, the film is sealingly connected with the lowerbase and to the wall body through a seam, in particular through a rollseam. In another embodiment, the film is sealingly connected with thelower end of the wall body by means of a flange, which could also becalled raised edge or flared tube end. Optionally, a sealing adhesivecan be inserted into the seam or flange. In a further embodiment, thefilm is connected with the lower base by means of anadhesion-connection, by sealing or through aform-fitting-(positive-locking fit) connection.

In a further embodiment, the upper base is sealingly connected with thewall body through a seam, in particular a roll seam, or a flange.

The opening in the upper base can, in accordance with a furtherexemplary embodiment of the invention, be realized as a screwing funnelhaving a screw thread for a screw cap or a cam screw cap. In this case,only the screwing funnel or the upper base including the screwing funnelcan consist for example of aluminum (or an aluminum alloy). In a furtherembodiment, the container comprises a screwing- or cam-screw-connectionmade of a metal. The screwing- or cam-screw-connection can for example(also) consist of aluminum (or of an aluminum alloy). Optionally, thescrewing- or cam-screw-connection can be coated or lacquered with abisphenol A (BPA)-free lacquer at least on those surfaces which, afterfilling, may come into contact with the liquid.

The cap or closure can comprise an inlying seal, for example made of apolymer. The polymer should be selected such that it does not liquefy orotherwise to decompose and contaminate the filled liquid atfilling-temperatures of about 80° C. or more.

The container can for example be closable with a crown cork instead of ascrewing- or cam-screw-closure. Generally and in particular when sealingthe container with a crown cork, the opening can be reinforced at itstop edge.

In a further embodiment, the lower base and/or the wall body comprises asheet metal, in particular tinplate. In a further embodiment, the upperbase at least partially comprises a sheet metal, in particular tinplate.In more general terms, the wall body and optionally the upper baseand/or the lower base can contain iron and in particular be a steel,preferably a stainless high-grade-steel.

In a further embodiment of the invention, the relation of the filmthickness and the thickness of the sheet is at least 1.5:1 andpreferably 2:1.

In a further embodiment, the surfaces of the upper base and/or of thewall body made of tinplate which are, after filling, in contact with theliquid, are provided with a BPA-free coating. It can furthermore beadvantageous if at least the junctions or interfaces of the upper baseand/or of the wall body are provided with a BPA-free powder seam cover.The coating can for example be realized with a BPA-free powder coating.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described on the basis of embodimentsthat refer to the attached figures. Corresponding components of thedetails in the figures are provided with the same reference numerals.

FIG. 1 shows a section view (cf. line E in FIG. 6) of a containeraccording to one embodiment of the invention;

FIG. 2 shows a further sectional view (cf. FIG. 6) of the containeraccording to FIG. 1, wherein, however, the film 16 extends dome-likeinto the inner space of the container;

FIG. 3 shows a magnified view of detail A of FIG. 2;

FIG. 4 shows a magnified view of detail B of FIG. 1;

FIG. 5 shows a magnified view of detail C of FIG. 2;

FIG. 6 shows a view on the lower base of the container according to oneembodiment of the invention;

FIG. 7 shows a view onto the lower base of the container according toanother embodiment of the invention;

FIG. 8 shows a perspective view of the container according to oneembodiment of the invention;

FIG. 9 shows a sectional view (cf. Line E in FIG. 6) of a containeraccording to a further embodiment of the invention;

FIG. 10 shows a view of a octagonal lower base of a container accordingto another embodiment of the invention;

FIG. 11 shows a perspective view of the octagonal container;

FIG. 12 shows a view of an oval lower base of a container according toanother embodiment of the invention; and

FIG. 13 shows a perspective view of the oval container.

DETAILED DESCRIPTION

The invention relates to a container suitable for hot-filling of foodproducts in liquid form. In embodiments of the invention, the containeris made of metal or of a metal alloy. An exemplary container accordingto one such embodiment of the invention is shown in a perspective viewin FIG. 8. The container shown therein is designed in bottle-shape. Theshape of the container is essentially defined by its lower base 11, itsupper base 12 and a wall body 13 forming a side wall, which in thisembodiment is designed as a hollow cylinder (cf. FIG. 6 and thesectional view in FIG. 1 along the section-line E indicated in FIG. 4).The lower base 11 and the upper base 12 are in this embodimentcorrespondingly formed circularly. Furthermore, the container alsocomprises a film 16 provided between the lower base 11 and the lower endof the sidewall 13. The terms “upper” and “lower” as used herein canrefer to the preferred position of the respective components of thecontainer, particularly in an upright position in which (only) the lowerbase 11 is in contact with a ground on which container stands (forexample when the container is filled with a liquid), such that theopening 14 for receiving and/or dispensing the liquid faces upwards (andso that no liquid is lost in this position).

The lower base 11 consists of a metal (or a metal alloy) the lower basecomprises an air admission or passage 41 which,—as will be explained indetail below—allows replenishing flow of (surrounding) air when the film16 deforms in order to realize a volume reduction of the bottleinterior.

The upper base 12 also consists of a metal (or of a metal alloy). Theupper base 12 comprises an opening for receiving the fluid. The opening14 of the upper base 12 is arranged axially centric (cf. also FIG. 6).Naturally, it is also possible not to arrange the opening of thecontainer centrally, for example offset towards the edge of the upperbase 12.

The upper base 12 is realized funnel-shaped in the shown embodiment andcan thus also be called a funnel. The opening 14 of the upper base 12can for example be formed as a screwing-funnel having a thread 15 and ascrewing- or cam-screw-closure 81. The closure or cap 81 is an optionalelement of the container. A thread for closing or sealing the containeris not necessarily required. For example, the container canalternatively also be closed with a crown cork or with a swing top (alsoreferred to as flip top). In particular when closing the container witha crown cork it is reasonable to provide a reinforcement at the upperedge or end of the opening 14.

The upper base 12 and the lower base 11 are sealingly connected at theirrespective end area with the outside wall 13 of the container, which isin this embodiment cylindrical, so that the hollow space is formed intowhich for example a liquid can be filled. The container is thereforeformed single-walled and the inserted or filled liquid is situated in adirect contact with the side wall 13 (i.e.: at least parts of thesidewall 13).

Between the lower base 11 and lower end of the sidewall of 13, sealinglyengaging the lower base 11, a film 16 is provided. The film 16 can causea volume reduction of the hollow space, as exemplarily shown in FIG. 2.When the bottle is sealed gas-tight, for example after hot-filling thecontainer with the liquid, differences between the pressure within thehollow space of the container and the atmospheric pressure outside ofthe container can be balanced through a corresponding deformation of thefilm 16, causing a volume reduction of the inner space of the container.For example after hot-filling of the container with a liquid, and afterclosing the container in a state with a still hot liquid, and subsequentcooling of the liquid, an under pressure can occur in the inside of thecontainer. The volume reduction required for pressure-compensationbetween the atmospheric pressure of the interior pressure of thecontainer can be realized with the aid of the film 16. The film 16absorbs the arising tensile forces and deform relative to the lower base11 towards the interior of the hollow space of the container in a dome-or cupola-like manner, as for example shown in FIG. 2. In other terms,the difference between the interior pressure of the container and theatmospheric exterior pressure is compensated through deforming the film16 due to the pressure-force resulting from the pressure-difference(elastically and/or plastically) such that an effective decrease of thevolume of the container interior occurs. The compression of the liquidfollowing its cooling thus causes a corresponding size reduction of thevolume of the container interior due to the deformation of the film. Inthis way it is avoided that a visible deformation of the sidewall 13and/or of the upper base 12 occurs by avoiding the occurrence ofpressure forces acting on to the sidewall 13 and onto the upper base 12which achieve a magnitude sufficient for their respective deformation.

In order to ensure that the required volume reduction is significantlyachieved through the deformation of the film 16 and in particular thatthe sidewall 13 remains in its cylindrical basic shape, the material ofthe sidewall 13 is for example to be selected such that it isdeformation-rigid in contrast to the material of the film 16. The lowerbase 11 comprises in the embodiment a centrally formed air admission 41(cf. FIG. 4) through which, during the deformation of the film 16towards the inside of the container, air can flow into the formingintermediate space 21 between the lower base 11 and the film 16.

In one embodiment, the sidewall (wall body) 13 is formed of a sheetmetal, in particular of a tinplate. The film 16 can also be made of ametal (or of a metal alloy) however, also other material can beconsidered, such as polymers. For example, the film 16 can also consistof a polycarbonate, such as polyester. Since the film 16 is in contactwith the liquid after hot-filling the container, it is important that nochemical reaction occurs between the material of the film 16 and theliquid changing the taste of the food product within the container. Thisis of importance in particular for the filling of sugar-containing foodproducts, in particular syrup (such as maple syrup) since it has beenshown that sheets (tinplate) in direct contact with sugar-containingsyrup (in particular maple syrup) experience chemical reactions and thatthis results in detrimental changes of the taste of the food product.

In an advantageous embodiment, the film 16 is made of aluminum (or analuminum alloy). It has been shown in experiments that, when aluminum isused, no change of the taste can be noticed of the maple syrup which hasbeen filled into the container. Accordingly, it is reasonable also tomake the upper base 12 from aluminum (or an aluminum alloy). It is also,optionally, possible to make the sidewall 13 of aluminum (or an aluminumalloy). For example, the mentioned aluminum can be pure aluminum (i.e.the film consists to at least 98% of aluminum).

When also the sidewall 13 consists of aluminum (or an aluminum alloy)this significantly increases the production costs of the container, sothat the complete cost of the container may no longer be competitive.Therefore, in another embodiment of the invention, the sidewall 13 ismade of a single piece of drawn sheet metal, in particular tinplate.Surfaces of the wall body which can come into contact with the filledliquid can be lacquered or coated. This is reasonable in particular ifit otherwise comes to a chemical reaction between the liquid of the wallbody and if such a reaction can be avoided with use of this measure.Advantageously, a BPA-free lacquer or a BPA-free coating is used forlacquering or coating.

Fundamentally, it is also possible that any surfaces of the upper base12 and the lower base 11 which are in touch with the liquid afterfilling are also provided with a BPA-free coating. The coating can forexample be a BPA-free powder coating.

The seams of the upper base 12 and/or of the wall body 13, which are incontact with the liquid after filling, can optionally be provided with apowder seam cover.

FIG. 3 shows the detail magnification A of FIG. 2. As shown in FIG. 3,the film 16 can for example be fastened between the lower base 11sidewall 13 of the cylindrical hollow body of the container. Preferably,the three layers, that is: the lower end of the hollow body of thesidewall 13, the film 16, and the edge section of the lower base 11, aresealingly connected with one another through a seam, in particular aroll seam. Alternatively it is also possible to sealingly connect the 3layers with one another through a flange. Optionally, a sealing adhesivecan be used in the contact area of the sidewall 13 of the film 16 and ofthe lower base 11 for both the seam as well as the flange. Thereby itshould be ensured that the sealing adhesive does not extend between thefilm 16 and the inside of the wall 13 towards the container interior sothat it does not come into contact with the filled-in liquid.

FIG. 4 shows a detail magnification of FIG. 1. In the original(non-deformed) state of the film 16, the film 16 lies engaging on thelower base 11, wherein, for example centrally or axially centered, oneair passage 41 is provided in the lower base.

FIG. 5 shows a detail magnification of detail C in FIG. 2. As apparentfrom FIG. 5, due to a deformation of the film 16 through the air passage41 (surrounding-) air can flow into the arising hollow space 21 betweenthe film 16 and the lower base, so that the atmospheric outside pressureof the container also prevails in the intermediate space 21 and nounderpressure is created in the intermediate space 21.

FIG. 6 shows a cross-section of the container of FIG. 1 along thesection line D shown therein, wherein the film 16 is not illustrated. Inthe shown embodiment, the air passage 41 is arranged centrally in thelower base 11. The air passage can, however, also be arranged at anotherposition, as long as it is ascertained, that the (surrounding) air cankeep streaming through the air passage 41 into the space 21 which isformed during deformation of the film 16 between the lower base 11 andthe film 16. It is also possible to provide multiple air passages in thelower base 11. FIG. 7 shows an exemplary further embodiment of the lowerbase 11 comprising 5 air passages 41 a-41 e. The air passage or the airpassages, respectively, 41 can for example be realized by drilling,stamping, or the like.

Alternative to the solution shown in FIG. 4, the film seam could also beconnected with the lower base 11 through an adhesive connection orthrough sealing. In these alternatives, the shape and/or area of thefilm 16 does not need to be equal to the shape or area of the lower base11. The film 16 could for example be designed smaller. One example isshown in FIG. 9, in which a circular film 16 has a smaller base areathan the lower base 11 and is adhered along its circumference in an area92. In case the container is intended for hot-filling, the melting pointof the (hardened) adhesive 91 should lie above the filling temperatureof the liquid so as to avoid melting of the adhesive 91.

A further possibility lies in connecting the film 16 to the lower base11 to be form-fitted.

The shape of the container is not limited to a cylindrical wall body 13and correspondingly formed lower base 11 and upper base 12. FIG. 10 andFIG. 11 show further embodiments of the container having an octagonallower base 101, and octagonal upper base 102, and a correspondingoctagonal cylinder sidewall 103. A further possible embodiment of thecontainer is shown in FIGS. 12 and 13. The container shown thereincomprises an oval (elliptic) lower base 121, an oval upper base 122 and,and a corresponding oval cylinder is a sidewall 123.

As illustrated in FIGS. 11 and 13, the opening 14 can also in theseembodiments comprise a thread 15. The opening 14 can also, as in theprevious embodiments, for example be closed with a screw- orcam-screw-closure 81. The provision of a thread 15 for closing thecontainer with a screw- or cam-screw-81 is not mandatorily required. Forexample, the container as shown in FIGS. 11 and 13 could alternativelybe closed with a crown-cork or flip-top (also referred to as aspring-top). In such cases it is possible to reinforce the opening oraperture 14 of the container.

A further aspect of the invention further relates to a filling method,in which the container according to the invention is hot-filled with theliquid, in particular with a food product in liquid or viscousform/state, for example through the funnel and/or the opening in theupper base. The food product can for example be a highlysugar-containing food product, such as a syrup (for example maplesyrup). During hot filling, the container according to the invention isfilled with the hot liquid. The liquid had for example a temperature ofat least 80° C. In another example, the filling temperature lies between80° C. and 100° C., or between 85° C. and 90° C.

During filling of the container, hot liquid does not need to be foamedwith water or water-steam before closing the container, nor does aninert gas (shielding gas) have to be inserted between the upper rim ofthe opening 14 and the surface of the liquid, so that the container isparticularly suitable for the use in a simple fill and seal method witha simply constructed fill and seal machine.

What is claimed is:
 1. A container for receiving a liquid, wherein thecontainer comprises: an upper base made of a metal or an alloy having anopening for receiving the liquid; a lower base made of a metal or analloy having an air admission, wherein the upper base and the lower baseare sealingly connected with a wall body at the upper end and the lowerend of the wall body, respectively, to form a hollow space for receivingthe liquid, said wall body being made of a metal or an alloy; and, afilm that can realize a volume reduction of the hollow space is providedbetween the lower base and the lower end of the wall body that issealingly in contact with the lower base.
 2. A container according toclaim 1, wherein the wall body and optionally the upper base and/or thelower base are deformation-resistant in relation to the film.
 3. Acontainer according to claim 1, wherein the film compensates compressionforces such that the outer shape of the wall body of the container doesnot deform due to tensile forces during cooling of a hot-filled liquid.4. A container according to claim 1, wherein the film compensatescompression forces such that the outer shape of the entire containerdoes not deform due to tensile forces during cooling of the hot-filledliquid.
 5. A container according to one of the claim 1, wherein the wallbody is realized as a hollow cylinder.
 6. A container according to claim5, wherein the material properties of the film absorb the compressionforces so entirely that the cylindrical shape of the wall body remainsintact after cooling of the liquid.
 7. A container according to claim 1,wherein the film together with the lower base and the wall body aresealingly connected with one another through a seam, in particular aroll seam.
 8. A container according to claim 1, wherein the filmtogether with the lower base and the wall body are sealingly connectedwith one another through a flange.
 9. A container according to claim 7,wherein a sealing adhesive is inserted into the seam.
 10. A containeraccording to claim 1, wherein the film is connected with the lower baseby means of an adhesive connection, by sealing or through apositive-locking fit connection.
 11. A container according to claim 1,wherein the upper base is sealingly connected with the wall body througha seam, in particular a roll seam, or a flange.
 12. A containeraccording to claim 1, wherein the opening is realized as a screwingfunnel having screw threads for a screw cap or a cam screw cap.
 13. Acontainer according to claim 12, wherein only the screwing funnel or theupper base including the screwing funnel consist of aluminum or analuminum alloy.
 14. A container according to claim 12, furthercomprising a screw cap or cam screw cap including an inlying seal, saidscrew cap or cam screw cap made of metal, optionally of aluminum or analuminum alloy, and further wherein the screw cap or cam screw cap iscoated with a BPA-free lacquer at least on the surfaces which can comeinto contact with the liquid after filling.
 15. (canceled) 16.(canceled)
 17. A container according to claim 1, wherein the containerfurther comprises a swing top.
 18. A container according to claim 1,wherein the opening is reinforced at the upper end thereof. 19.(canceled)
 20. A container according to claim 1, wherein the lower base,the wall body, and at least a portion of the upper base, are made of asheet metal, in particular tinplate, and the relation between thethickness of the film and the thickness of the sheet metal is at least1.5:1 and preferably 2:1.
 21. (canceled)
 22. (canceled)
 23. (canceled)24. A container according to claim 1, wherein the surfaces of the upperbase and of the wall body which after filling are in contact with theliquid are made of tinplate and are provided with a BPA-free coating.25. A container according to claim 1, wherein at least the junctions ofthe upper base and of the wall body which are in contact with the liquidafter filling are provided with a BPA-free powder seam cover, optionallya BPA-free powder coating.
 26. (canceled)
 27. A container according toclaim 1, wherein the wall body and optionally the upper base and/or thelower base comprise iron and are in particular a steel.
 28. A containeraccording to claim 8, wherein a sealing adhesive is inserted into theflange.